Basic/B2a Example

It is equivalent to the B2a example in Geant4 but re-written with a new more Julia friendly interface. The core of the example is to create an instance of the type G4JLApplication with all the essential elements defined (detector and geometry, physics list, primary particles generator, actions, simulated data being accumulated, mapping of logical volumes to sensitive detectors, etc.)

Import the `Geant4` and `Geant4.SystemOfUnits` modules

using Geant4
using Geant4.SystemOfUnits
using Printf, GeometryBasics

Define the Detector Parameters and Geometry

We include a file to define de structure B2aDetector and the construction method B2aConstruct to make the notebook more manageable

include(joinpath(@__DIR__, "DetectorB2a.jl"))

Define TrackerHit structure

struct TrackerHit
    trackID::Int32
    chamberNb::Int32
    edep::Float64
    pos::Point3{Float64}
end
function Base.show(io::IO, hit::TrackerHit)
    (;trackID, chamberNb, edep, pos) = hit
    @printf(io, "\ntrackID: %3d chamberNb: %2d Edep: %.3f MeV Position: (%3f, %3f, %3f)", trackID, chamberNb, edep/MeV, pos...) 
end

Define Sensitive Detector for the chambers

It implies to define a data structure where to accumulate the TrackerHits for each event, and the callback functions:

intilialize called at the beginning of each event
endOfEvent called at the end of the event
processHit called for each hit (step ending in the associated logical volume) to be processed

all of the callback functions get the declared data structure as first argument

#---SD collected data------------------------------------------------------------------------------
struct B2aSDData <: G4JLSDData
    trackerHits::Vector{TrackerHit}
    B2aSDData() = new([])
end
#---Initialize method------------------------------------------------------------------------------
function _initialize(data::B2aSDData, ::G4HCofThisEvent)::Nothing
    empty!(data.trackerHits)
    return
end
#---End of Event method----------------------------------------------------------------------------
function _endOfEvent(data::B2aSDData, ::G4HCofThisEvent)::Nothing
    return
end
#---Process Hit method-----------------------------------------------------------------------------
function _processHits(data::B2aSDData, step::G4Step, ::G4TouchableHistory)::Bool
    edep = step |> GetTotalEnergyDeposit
    edep <  0. && return false
    pos = step |> GetPostStepPoint |> GetPosition
    push!(data.trackerHits, TrackerHit(step |> GetTrack |> GetTrackID,
                                       step |> GetPreStepPoint |> GetTouchable |> GetCopyNumber,
                                       edep,
                                       Point3{Float64}(x(pos),y(pos),z(pos))))
    return true
end

_processHits (generic function with 1 method)

And create a specialized instance of G4JLSensitiveDetector

#---Create SD instance-----------------------------------------------------------------------------
chamber_SD = G4JLSensitiveDetector("Chamber_SD", B2aSDData();           # SD name an associated data are mandatory
                                    processhits_method=_processHits,    # process hist method (also mandatory)
                                    initialize_method=_initialize,      # intialize method
                                    endofevent_method=_endOfEvent);     # end of event method

Define an End Event Action

This is collect all results each event. Only printing at this time.

#---End Event Action-------------------------------------------------------------------------------
function endeventaction(evt::G4Event, app::G4JLApplication)
    hits = getSDdata(app, "Chamber_SD").trackerHits
    eventID = evt |> GetEventID
    if eventID < 10 || eventID % 100 == 0
      G4JL_println("Event: $eventID with $(length(hits)) hits stored in this event")
    end
    return
  end

endeventaction (generic function with 1 method)

Define the primary particle generator (Particle Gun)

particlegun = G4JLGunGenerator(particle = "proton", 
                               energy = 3GeV, 
                               direction = G4ThreeVector(0,0,1), 
                               position = G4ThreeVector(0,0,-2940.0))

G4JLGunGenerator("ParticleGun", Geant4.G4JLParticleGunData(nothing, "proton", Geant4.CLHEP!Hep3VectorAllocated(Ptr{Nothing} @0x000000000153c550), Geant4.CLHEP!Hep3VectorAllocated(Ptr{Nothing} @0x00000000022feb30), 3000.0), Geant4.var"#init#24"(), Geant4.var"#gen#25"(), G4JLGeneratorAction[])

Instantiate a `G4JLApplication` with all the elements

The G4RunManager is created at this moment

#---Create the Application-------------------------------------------------------------------------
app = G4JLApplication( detector = B2aDetector(nChambers=5),          # detector with parameters
                       generator = particlegun,                      # primary particle generator
                       nthreads = 4,                                 # number of threads (MT)
                       physics_type = FTFP_BERT,                     # what physics list to instantiate
                       endeventaction_method = endeventaction,       # end event action
                       sdetectors = ["Chamber_LV+" => chamber_SD]    # mapping of LVs to SDs (+ means multiple LVs with same name)
                      );

**************************************************************
 Geant4 version Name: geant4-11-01-patch-01 [MT]   (10-February-2023)
  << in Multi-threaded mode >> 
                       Copyright : Geant4 Collaboration
                      References : NIM A 506 (2003), 250-303
                                 : IEEE-TNS 53 (2006), 270-278
                                 : NIM A 835 (2016), 186-225
                             WWW : http://geant4.org/
**************************************************************

Final steps

Configure the application, initialize the run and fire the beam for 0 events to finalize all initializations

configure(app)

initialize(app)

Checking overlaps for volume Target:0 (G4Tubs) ... OK! 
Checking overlaps for volume Tracker:0 (G4Tubs) ... OK! 
Checking overlaps for volume Chamber_PV:1 (G4Tubs) ... OK! 
Checking overlaps for volume Chamber_PV:2 (G4Tubs) ... OK! 
Checking overlaps for volume Chamber_PV:3 (G4Tubs) ... OK! 
Checking overlaps for volume Chamber_PV:4 (G4Tubs) ... OK! 
Checking overlaps for volume Chamber_PV:5 (G4Tubs) ... OK!

beamOn(app, 0)

#---Forcing the loading of G4Vis extension------------------------------------------
using WGLMakie
using Rotations, IGLWrap_jll

world = GetWorldVolume()
draw(world)

WGLMakie.Screen(Channel{WGLMakie.ThreeDisplay}(1), Session{JSServe.SubConnection}:
  id: 126a05cc-636f-41c3-b88b-f0c0ad03d4d5
  parent: JSServe.Session{JSServe.IJuliaConnection}
  connection: closed
  isready: false
  asset_server: JSServe.NoServer
  queued messages: 0
, true, Scene (1280px, 720px):
  0 Plots
  1 Child Scene:
    └ Scene (1280px, 720px), Set{String}())

beamOn(app,10)

G4WT1 > Event: 1 with 131 hits stored in this event
G4WT1 > Event: 4 with 84 hits stored in this event
G4WT2 > Event: 0 with 105 hits stored in this event
G4WT1 > Event: 5 with 77 hits stored in this event
G4WT1 > Event: 7 with 76 hits stored in this event
G4WT1 > Event: 8 with 75 hits stored in this event
G4WT1 > Event: 9 with 135 hits stored in this event
G4WT3 > Event: 3 with 75 hits stored in this event
G4WT0 > Event: 2 with 70 hits stored in this event
G4WT2 > Event: 6 with 319 hits stored in this event

@time beamOn(app,1000)

G4WT3 > Event: 0 with 57 hits stored in this event
G4WT3 > Event: 1 with 202 hits stored in this event
G4WT3 > Event: 2 with 55 hits stored in this event
G4WT3 > Event: 3 with 128 hits stored in this event
G4WT3 > Event: 4 with 15 hits stored in this event
G4WT3 > Event: 5 with 205 hits stored in this event
G4WT3 > Event: 6 with 224 hits stored in this event
G4WT3 > Event: 7 with 124 hits stored in this event
G4WT3 > Event: 8 with 213 hits stored in this event
G4WT3 > Event: 9 with 50 hits stored in this event
G4WT2 > Event: 100 with 93 hits stored in this event
G4WT0 > Event: 200 with 89 hits stored in this event
G4WT3 > Event: 300 with 113 hits stored in this event
G4WT2 > Event: 400 with 60 hits stored in this event
G4WT2 > Event: 500 with 71 hits stored in this event
G4WT0 > Event: 600 with 64 hits stored in this event
G4WT3 > Event: 700 with 98 hits stored in this event
G4WT2 > Event: 800 with 167 hits stored in this event
G4WT0 > Event: 900 with 79 hits stored in this event
  1.251598 seconds (533.33 k allocations: 14.161 MiB)

SetParticleEnergy(particlegun, 500MeV)

@time beamOn(app,10000)

G4WT1 > Event: 0 with 139 hits stored in this event
G4WT1 > Event: 1 with 107 hits stored in this event
G4WT1 > Event: 2 with 160 hits stored in this event
G4WT1 > Event: 3 with 18 hits stored in this event
G4WT1 > Event: 4 with 359 hits stored in this event
G4WT1 > Event: 5 with 149 hits stored in this event
G4WT1 > Event: 6 with 193 hits stored in this event
G4WT1 > Event: 7 with 159 hits stored in this event
G4WT1 > Event: 8 with 179 hits stored in this event
G4WT1 > Event: 9 with 105 hits stored in this event
G4WT3 > Event: 100 with 300 hits stored in this event
G4WT2 > Event: 200 with 188 hits stored in this event
G4WT3 > Event: 300 with 240 hits stored in this event
G4WT1 > Event: 400 with 150 hits stored in this event
G4WT0 > Event: 500 with 245 hits stored in this event
G4WT2 > Event: 600 with 196 hits stored in this event
G4WT0 > Event: 700 with 190 hits stored in this event
G4WT2 > Event: 800 with 123 hits stored in this event
G4WT0 > Event: 900 with 188 hits stored in this event
G4WT1 > Event: 1000 with 112 hits stored in this event
G4WT0 > Event: 1100 with 130 hits stored in this event
G4WT1 > Event: 1200 with 4 hits stored in this event
G4WT0 > Event: 1300 with 255 hits stored in this event
G4WT3 > Event: 1400 with 159 hits stored in this event
G4WT2 > Event: 1500 with 145 hits stored in this event
G4WT3 > Event: 1600 with 144 hits stored in this event
G4WT0 > Event: 1700 with 150 hits stored in this event
G4WT3 > Event: 1800 with 189 hits stored in this event
G4WT0 > Event: 1900 with 115 hits stored in this event
G4WT3 > Event: 2000 with 220 hits stored in this event
G4WT2 > Event: 2100 with 164 hits stored in this event
G4WT3 > Event: 2200 with 95 hits stored in this event
G4WT2 > Event: 2300 with 167 hits stored in this event
G4WT1 > Event: 2400 with 179 hits stored in this event
G4WT2 > Event: 2500 with 251 hits stored in this event
G4WT0 > Event: 2600 with 192 hits stored in this event
G4WT2 > Event: 2700 with 155 hits stored in this event
G4WT0 > Event: 2800 with 5 hits stored in this event
G4WT2 > Event: 2900 with 12 hits stored in this event
G4WT0 > Event: 3000 with 182 hits stored in this event
G4WT2 > Event: 3100 with 255 hits stored in this event
G4WT0 > Event: 3200 with 161 hits stored in this event
G4WT2 > Event: 3300 with 136 hits stored in this event
G4WT0 > Event: 3400 with 154 hits stored in this event
G4WT2 > Event: 3500 with 237 hits stored in this event
G4WT1 > Event: 3600 with 167 hits stored in this event
G4WT2 > Event: 3700 with 136 hits stored in this event
G4WT0 > Event: 3800 with 187 hits stored in this event
G4WT2 > Event: 3900 with 232 hits stored in this event
G4WT0 > Event: 4000 with 230 hits stored in this event
G4WT2 > Event: 4100 with 178 hits stored in this event
G4WT3 > Event: 4200 with 144 hits stored in this event
G4WT2 > Event: 4300 with 142 hits stored in this event
G4WT1 > Event: 4400 with 125 hits stored in this event
G4WT2 > Event: 4500 with 174 hits stored in this event
G4WT1 > Event: 4600 with 213 hits stored in this event
G4WT2 > Event: 4700 with 210 hits stored in this event
G4WT1 > Event: 4800 with 121 hits stored in this event
G4WT0 > Event: 4900 with 130 hits stored in this event
G4WT1 > Event: 5000 with 220 hits stored in this event
G4WT0 > Event: 5100 with 145 hits stored in this event
G4WT1 > Event: 5200 with 180 hits stored in this event
G4WT0 > Event: 5300 with 148 hits stored in this event
G4WT1 > Event: 5400 with 107 hits stored in this event
G4WT0 > Event: 5500 with 168 hits stored in this event
G4WT1 > Event: 5600 with 147 hits stored in this event
G4WT0 > Event: 5700 with 181 hits stored in this event
G4WT2 > Event: 5800 with 290 hits stored in this event
G4WT0 > Event: 5900 with 173 hits stored in this event
G4WT3 > Event: 6000 with 4 hits stored in this event
G4WT1 > Event: 6100 with 13 hits stored in this event
G4WT3 > Event: 6200 with 138 hits stored in this event
G4WT1 > Event: 6300 with 143 hits stored in this event
G4WT3 > Event: 6400 with 247 hits stored in this event
G4WT1 > Event: 6500 with 152 hits stored in this event
G4WT3 > Event: 6600 with 144 hits stored in this event
G4WT1 > Event: 6700 with 160 hits stored in this event
G4WT3 > Event: 6800 with 4 hits stored in this event
G4WT0 > Event: 6900 with 115 hits stored in this event
G4WT3 > Event: 7000 with 186 hits stored in this event
G4WT0 > Event: 7100 with 249 hits stored in this event
G4WT3 > Event: 7200 with 177 hits stored in this event
G4WT2 > Event: 7300 with 170 hits stored in this event
G4WT3 > Event: 7400 with 270 hits stored in this event
G4WT2 > Event: 7500 with 4 hits stored in this event
G4WT1 > Event: 7600 with 164 hits stored in this event
G4WT2 > Event: 7700 with 191 hits stored in this event
G4WT1 > Event: 7800 with 116 hits stored in this event
G4WT3 > Event: 7900 with 181 hits stored in this event
G4WT0 > Event: 8000 with 4 hits stored in this event
G4WT1 > Event: 8100 with 149 hits stored in this event
G4WT0 > Event: 8200 with 259 hits stored in this event
G4WT1 > Event: 8300 with 3 hits stored in this event
G4WT0 > Event: 8400 with 114 hits stored in this event
G4WT1 > Event: 8500 with 165 hits stored in this event
G4WT1 > Event: 8600 with 105 hits stored in this event
G4WT0 > Event: 8700 with 136 hits stored in this event
G4WT1 > Event: 8800 with 309 hits stored in this event
G4WT0 > Event: 8900 with 364 hits stored in this event
G4WT1 > Event: 9000 with 123 hits stored in this event
G4WT3 > Event: 9100 with 238 hits stored in this event
G4WT3 > Event: 9200 with 170 hits stored in this event
G4WT1 > Event: 9300 with 0 hits stored in this event
G4WT3 > Event: 9400 with 165 hits stored in this event
G4WT0 > Event: 9500 with 190 hits stored in this event
G4WT0 > Event: 9600 with 209 hits stored in this event
G4WT3 > Event: 9700 with 101 hits stored in this event
G4WT1 > Event: 9800 with 166 hits stored in this event
G4WT0 > Event: 9900 with 126 hits stored in this event
  7.801641 seconds (5.21 M allocations: 80.134 MiB)